What you can learn from Warren Buffett’s mistakes
There was very little news in the annual letter to Berkshire Hathaway shareholders that Warren Buffett released Saturday morning. Buffett did mention that “Berkshire had a good year in 2022,” with operating earnings of US$30.8 billion ($41.6 billion), and disclosed that subsidiary See’s Candies sold US$400,309, or 11 tonnes, of its peanut brittle and chocolates at last year’s annual meeting in Omaha. But the main thing that stood out about the letter was its brevity — at 4,455 words — it was the shortest Buffett shareholder letter in 44 years.
Yes, I began assembling this data before the new letter came out — I suspected there might not be much else to discuss. The trajectory already gave the unmistakable signal that the Berkshire chairman was winding things down. And, well, he is: Buffett is 92, while his long-time business partner, Berkshire vice chairman Charles Munger, is 99.
The big spike on the chart is from the 2014 letter (published in February 2015), when Buffett offered a look back at the 50 years since he had taken control of a faltering Massachusetts textile manufacturer and began its long transformation into an investment vehicle and industrial giant; Munger chimed in with his 2,430-word review. This look back involved acknowledging many mistakes, which has become a Buffett trademark. His 25-anniversary review was titled Mistakes of the First Twenty-five Years (A Condensed Version). The latest missive included four uses of the word, too, which, relative to the letter’s small overall word count, turns
out to be a lot by Buffett standards.
In the letter accompanying Berkshire’s 1985 annual report, Buffett attributed the focus on mistakes to Munger, who “has always emphasised the study of mistakes rather than successes, both in business and other aspects of life.” Such emphasis is not the norm among American investing icons and corporate superstars. I looked through the oeuvre of Amazon.com founder and former CEO Jeff Bezos, also known for his smart shareholder letters, and in 24 years of letters, found just five uses of “mistake,” only three of which could be construed as Bezos acknowledging that he had made or might make one.
Not all the Buffett “mistakes” tallied above were his, but most were. After attempting to separate the non-confessional uses of the word in the Berkshire letters and being hampered by several judgment calls, I decided they should all count.
Does the frequency of their use tell us anything? The Berkshire shareholder letters feature a table comparing the company’s stock price performance yearly since 1965 with the total return of the Standard & Poor’s 500 Index. Subtract the second from the first to measure Berkshire’s relative performance, and the result turns out to be correlated with the frequency of “mistake” appearances in the shareholder letter for that year. The r-squared is 0.33, implying that Berkshire’s relative performance “explains” a third of the mistake frequency in the letters. This makes sense — most of us are more generous about acknowledging our faults when things are going well.
More generally, it’s easy to say things like “most of my capital-allocation decisions have been no better than soso,” as Buffett does in his latest letter if you’re widely acknowledged as one of the world’s greatest-ever capital allocators. This exercise might be more informative if it included more of the pre-success, pre-fame Buffett, with letters to investors in his Buffett Partnership and Berkshire shareholder letters predating those that the company makes available on its website. Maybe next time (getting all those letters into searchable form might take a while).
Or maybe not — all this number-crunching is, I’ll admit, a bit silly. But it’s interesting, right? And you still want to know whether Buffett’s “mistake” mentions predicting future Berkshire performance, right?
On a short-term basis, the answer is no. The correlation between “mistake” frequency in the shareholder letter and Berkshire’s subsequent one-year performance relative to the S&P 500 is zero. However, Buffett has always been disdainful of short-term performance metrics, so I also looked into the link between mistake mentions and average outperformance over the subsequent five years. Sure enough, there is one, with an r-squared of 0.32 and a p-value (the probability of obtaining such a result by random chance) of just 0.001.
This is mainly testimony to the limitations of such statistical tests. I don’t think Warren Buffett’s heavy use of the word “mistake” in his late1970s shareholder letters was responsible for Berkshire outperforming the S&P 500 by an average of 30 percentage points a year from 1979 through 1989. But there are worse lessons one can take from Buffett’s investing success than that acknowledging and examining mistakes pays off. —